Rapid synthesis method of oil-soluble thick oil viscosity reducer

Abstract

The invention discloses a rapid synthesis method of an oil-soluble thick oil viscosity reducer, and relates to the technical field of petrochemical engineering, the rapid synthesis method comprises the following steps: mixing a monomer and a catalyst solution, premixing and filtering to obtain a precursor solution, carrying out photocatalytic copolymerization through a micro-channel reactor, monitoring molecular weight on line, regulating and controlling parameters through a PID algorithm, distilling to recover a solvent, precipitating and separating a crude product, and obtaining the oil-soluble thick oil viscosity reducer. The method disclosed by the invention has the advantages that the number-average molecular weight and the weight-average molecular weight of the polymer are accurately monitored in real time by connecting the laser particle analyzer and the multi-angle light scatterometer at the outlet end of the reactor in series, and the reaction temperature and the material flow velocity are dynamically regulated and controlled in combination with a proportional-integral-differential algorithm; the growth and termination behaviors of molecular chains in the polymerization process are accurately intervened, so that the molecular weight distribution index of the product is stably maintained in a preset range, the prepared viscosity reducer is high in molecular structure regularity, and meanwhile, the performance stability of the product in the storage and use processes is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and specifically to a rapid synthesis method of an oil-soluble heavy oil viscosity reducer. Background Art

[0002] As an important part of petroleum resources, heavy oil faces great challenges in the processes of exploitation, transportation, and processing due to its high viscosity and high asphaltene content. Oil-soluble heavy oil viscosity reducers are one of the key means to solve the problem of heavy oil fluidity by improving the dispersion of resins and asphaltenes in heavy oil and reducing the viscosity of crude oil. Currently, the research on oil-soluble viscosity reducers mainly focuses on polymer materials. Among them, viscosity reducers represented by olefin copolymers have become a research hotspot in this field due to their strong molecular structure designability and high viscosity reduction efficiency.

[0003] There are certain defects in the prior art. Firstly, the molecular weight distribution is uncontrollable during the synthesis of oil-soluble heavy oil viscosity reducers in the prior art, resulting in poor product dispersion and unstable viscosity reduction efficiency. Secondly, the impurity residue rate is high and the purity is insufficient after the synthesis of the prior art viscosity reducer, resulting in low solubility and easy stratification and attenuation during storage. Therefore, we propose a rapid synthesis method of an oil-soluble heavy oil viscosity reducer. Summary of the Invention

[0004] The purpose of the present invention is to provide a rapid synthesis method of an oil-soluble heavy oil viscosity reducer.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A rapid synthesis method of an oil-soluble heavy oil viscosity reducer, the synthesis method comprising the following specific steps:

[0006] Step 1: Mix methyl oleate monomer (molecular structure: CH3(CH2)7CH=CH(CH2)7COOCH3) with analytical pure styrene monomer (molecular structure: CH2=CHC6H5) to prepare a homogeneous mixture. Weigh a visible light-responsive catalyst, oxanthrenanthrene derivative, and dissolve the catalyst in anhydrous ethyl acetate to prepare a catalytic solution.

[0007] Step 2: Pump the mixture and the catalytic solution into a premixing tank, stir, and then filter to remove impurities through an internal filter to obtain a clear and transparent reaction precursor solution.

[0008] Step 3: Inject the reaction precursor solution into a quartz microchannel reactor, and an LED light source group is surrounded around the reactor. The catalyst absorbs photon energy to initiate the alternating copolymerization of the carbon-carbon double bonds of methyl oleate and styrene to form an oil-soluble viscosity reducer prepolymer.

[0009] Step 4: Connect a laser particle size analyzer and a multi-angle light scattering analyzer in series at the outlet end of the reactor to monitor the number-average molecular weight (M n ) and weight-average molecular weight (Mw ) Calculate the molecular weight distribution index PDI = M n / M w , and dynamically regulate the reaction temperature and material flow rate based on the proportional-integral-differential algorithm to ensure that the PDI of the final product is stably maintained at 1.2 - 1.5;

[0010] Step Five: The reaction effluent enters a vacuum distillation device to separate the ethyl acetate solvent. The recovered solvent is dried by molecular sieve and recycled. The distillation residue is cooled to room temperature, and analytical pure n-hexane is added for precipitation. The white flocculent polymer crude product is obtained by centrifugation;

[0011] Step Six: Dissolve the polymer crude product in HPLC-grade tetrahydrofuran, wash it with deionized water successively. The washed organic phase is further purified through a chromatography column filled with neutral alumina. The purified solution is removed of the solvent by a rotary evaporator to obtain a transparent polymer. The transparent polymer is placed in a vacuum drying oven for drying treatment, and finally a light yellow powdery viscosity reducer is obtained;

[0012] Step Seven: Perform multi-dimensional performance tests on the dried product, including measuring the molecular weight and distribution by gel permeation chromatography, measuring the oil solubility by the equilibrium solubility method, measuring the viscosity reduction performance by a rotary viscometer, and measuring the thermal stability by thermogravimetric analysis. After passing the tests, it is packaged and stored.

[0013] As a further solution of the present invention: In the first step, the purity of the methyl oleate monomer selected is ≥98%. The methyl oleate monomer and the analytical pure styrene monomer are put into a stainless-steel raw material tank according to the molar ratio of 3 - 3.5:1. Start stirring and stir at a speed of 200 rpm - 300 rpm, and at the same time heat up to 40°C - 45°C until a homogeneous mixture is formed. Weigh a visible light-responsive catalyst oxanthrene anthracene derivative accounting for 0.05% - 0.1% of the total mass of the monomers. It has a conjugated anthracene ring skeleton and symmetrically distributed alkyl substituents, and can improve the light absorption efficiency through intramolecular π-π conjugation effect. Through the regulation of the intramolecular π-π conjugation effect and the steric hindrance of the alkyl chain, the molar extinction coefficient of the catalyst at 420 nm - 480 nm is ≥2.8×10 4 M -1 cm -1 , and dissolve the catalyst in anhydrous ethyl acetate with a water content of 0.05% - 0.1% to prepare a catalytic solution with a concentration of 0.5 mol / L - 0.7 mol / L.

[0014] As a further solution of the present invention: in the second step, the monomer mixture and the catalytic solution are pumped into a premixing tank with jacket temperature control at a volume ratio of 13 - 15:1, and stirred at a speed of 300 rpm - 500 rpm for 10 min - 20 min in an environment of 25°C - 35°C to ensure uniform dispersion of the catalyst. Subsequently, the material passes through a filter with an internal 0.1 μm - 0.2 μm ceramic membrane, and impurity particles are removed under a filtration pressure of 0.3 MPa - 0.5 MPa.

[0015] As a further solution of the present invention: in the third step, the reaction precursor solution is injected into a quartz microchannel reactor with an inner diameter of 80 μm - 100 μm at a flow rate of 1.2 mL / min - 1.5 mL / min. The total length of the channel is 70 cm - 100 cm, and an LED light source group with a wavelength of 385 nm - 450 nm is surrounded around the reactor. The light intensity is stabilized at 15 mW / cm 2 - 20 mW / cm 2 , and the catalyst absorbs photon energy to initiate the alternating copolymerization of the carbon - carbon double bonds of methyl oleate and styrene. Under the constant temperature condition of 25°C - 35°C, the specific reaction equation is as follows:

[0016] Catalyst excitation, after the catalyst (cat) absorbs a photon (hv), it transitions from the ground state to the excited state (cat * ):

[0017]

[0018] Free radical initiation, the excited state catalyst (cat * ) initiates the formation of a radical intermediate from methyl oleate (M1, CH3(CH2)7CH=CH(CH2)7COOCH3):

[0019]

[0020] Alternating chain growth, the radical intermediate undergoes an addition reaction with styrene (M2, CH2=CHC6H5), and then continues to alternately add with methyl oleate to grow the polymer chain:

[0021]

[0022] Overall polymerization reaction formula, generally speaking, n monomers of methyl oleate and n monomers of styrene undergo an alternating copolymerization reaction under the action of the excited state catalyst (cat * ) to generate an alternating copolymer:

[0023]

[0024] The residence time of the material in the microchannel is controlled within 2 min - 3 min. Through efficient microscale mass transfer and light intensity uniformity, a monomer conversion rate of ≥98% is achieved, and the alternating connection rate of methyl oleate and styrene is ≥95% as detected by 1 1H-NMR.

[0025] As a further solution of the present invention: in the fourth step, when the detected value deviates from the target range (1.2 ≤ PDI ≤ 1.5), the control system automatically adjusts the reaction temperature and the material flow rate according to the following formula:

[0026]

[0027] where ΔT is the temperature adjustment amount (°C), K pT is the proportional coefficient of temperature adjustment, and its value range is 0.5 - 1.2, K iT is the integral coefficient of temperature adjustment, and its value range is 0.1 - 0.3, K dT is the differential coefficient of temperature adjustment, and its value range is 0.05 - 0.2;

[0028] v new = v old ·[1 + α·(PDI set - PDI real ) + β∫(PDI set - PDI real )dt]

[0029] where v new is the corrected flow rate (mL / min), v old is the current flow rate, the proportional correction factor α = 0.05 - 0.15, and the integral correction factor β = 0.01 - 0.05;

[0030] Through the above differential regulation strategy, it is ensured that the PDI of the final product is stable at 1.2 - 1.5, and the response time of the regulation system is <15 seconds.

[0031] As a further solution of the present invention: in the fifth step, the ethyl acetate solvent is separated by a vacuum distillation device under the conditions of a vacuum degree of 10 kPa - 20 kPa and a temperature of 40 - 50 °C. Analytical pure n-hexane with a volume 5 - 8 times that of the solvent is added for precipitation, and the centrifuge speed is 5000 rpm - 7000 rpm, and the time is 10 min - 20 min.

[0032] As a further solution of the present invention: in the sixth step, the dissolution concentration of the polymer crude product in tetrahydrofuran is 20 g / L - 30 g / L. It is washed 3 - 5 times with deionized water of equal volume successively, and the washing time for each time is 8 min - 12 min to remove the residual catalyst and monomer. The purified chromatography column has a column diameter of 1 cm - 3 cm and a column height of 20 cm - 40 cm. The flow rate is controlled at 0.5 mL / min - 1.5 mL / min. The purified solution is removed of the solvent by a rotary evaporator at a temperature of 50°C - 60°C and a vacuum degree of 20 kPa - 30 kPa to obtain a transparent polymer. The polymer is placed in a vacuum drying oven and dried for 10 h - 12 h under the conditions of a temperature of 60°C - 70°C and a vacuum degree < 15 kPa.

[0033] As a further solution of the present invention: in the seventh step, for the molecular weight and distribution: it is measured by gel permeation chromatography, the mobile phase is tetrahydrofuran, the flow rate is 1.0 mL / min - 1.5 mL / min, and polystyrene is used as the standard sample. It is required that the number average molecular weight M n n = 15000 Da - 35000 Da, and the molecular weight distribution index PDI ≤ 1.5;

[0034] The oil solubility is measured by the equilibrium solubility method: Weigh 2.0 g - 2.2 g of the sample and add it to 20 mL - 23 mL of heavy oil at 50°C - 52°C. The viscosity of the heavy oil > 1000 mPa·s and the asphaltene content is 15% - 20%. After stirring and dissolving, centrifuge it at a centrifugal speed of 3000 rpm - 3100 rpm for 5 min - 7 min, and calculate the solubility ≥ 50 g / L;

[0035] The viscosity reduction performance is measured by a rotational viscometer: Use a rotational viscometer to measure the viscosity of the heavy oil containing 2% viscosity reducer under the conditions of a shear rate of 100 s -1 -110 s -1 and a temperature of 50°C - 52°C. It is required that the viscosity reduction rate ≥ 80%;

[0036] The thermal stability is measured by thermogravimetric analysis: Through thermogravimetric analysis, under the conditions of a nitrogen atmosphere and a heating rate of 10°C / min - 12°C / min, the initial decomposition temperature > 180°C;

[0037] The qualified products are packaged in aluminum foil bags by batch, accompanied by a quality report, and stored in an environment with a temperature of 20°C - 30°C and a humidity < 60%.

[0038] Adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] 1. By connecting a laser particle size analyzer and a multi-angle light scattering analyzer in series at the reactor outlet, the present invention monitors the number average molecular weight and weight average molecular weight of the polymer in real time, and combines the proportional-integral-derivative algorithm to dynamically regulate the reaction temperature and the material flow rate, solving the problem of uncontrollable molecular weight distribution in the synthesis of oil-soluble heavy oil viscosity reducers in the prior art. By adjusting the reaction parameters in real-time feedback, the growth and termination of molecular chains during the polymerization process are precisely controlled, enabling the molecular weight distribution index of the product to be stabilized within a preset range, significantly improving the uniformity of the molecular weight distribution compared to the traditional process. The viscosity reducer prepared thereby has a regular molecular structure, excellent dispersibility in heavy oil, can more effectively disrupt the asphaltene association network, improve the viscosity reduction efficiency and enhance the long-term stability.

[0040] 2. By subjecting the crude polymer to multiple steps of refining and purification treatment, including dissolving in HPLC-grade tetrahydrofuran, washing with deionized water to remove residual catalysts and monomers, and deeply purifying through a neutral alumina chromatography column, combined with a vacuum drying process, the present invention solves the problems of high impurity residue rate and insufficient purity after the synthesis of viscosity reducers in the prior art. Through the synergistic effect of washing with polar solvents and adsorption by the chromatography column, the catalyst residue amount is controlled at an extremely low level, while unreacted monomers and by-products are removed. Then, through multi-dimensional detection means such as gel permeation chromatography, equilibrium solubility method, rotational viscometer, and thermogravimetric analysis, the molecular weight distribution, oil solubility, viscosity reduction performance, and thermal stability of the viscosity reducer are accurately evaluated to ensure that all performance indicators of the product meet the actual requirements of heavy oil exploitation. The viscosity reducer prepared thereby has high solubility in low-water-content heavy oil, strong temperature resistance, and no stratification or performance degradation during long-term storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the method steps in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0042] The following further describes the specific embodiments of the present invention in conjunction with the drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention.

[0043] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] Please refer to the attached Figure 1 , a rapid synthesis method of an oil-soluble heavy oil viscosity reducer of the present invention, the synthesis method includes the following specific steps:

[0045] Step 1: Mix methyl oleate monomer (with a molecular structure of CH3(CH2)7CH=CH(CH2)7COOCH3) and analytical pure styrene monomer (with a molecular structure of CH2=CHC6H5) to prepare a homogeneous mixture. Weigh a visible light-responsive catalyst, xanthenoanthracene derivative, and dissolve the catalyst in anhydrous ethyl acetate to prepare a catalytic solution.

[0046] Step 2: Pump the mixture and the catalytic solution into a premixing tank. After stirring, filter out impurities through an internal filter to obtain a clear and transparent reaction precursor solution.

[0047] Step 3: Inject the reaction precursor solution into a quartz microchannel reactor. An LED light source group surrounds the reactor. The catalyst absorbs photon energy to initiate the alternating copolymerization of the carbon-carbon double bonds of methyl oleate and styrene, forming an oil-soluble viscosity reducer prepolymer.

[0048] Step 4: Connect a laser particle size analyzer and a multi-angle light scattering instrument in series at the outlet end of the reactor to monitor the number-average molecular weight (M n ) and weight-average molecular weight (M w ) of the polymer in real time. Calculate the molecular weight distribution index PDI = M n / M w , and dynamically regulate the reaction temperature and the material flow rate based on the proportional-integral-derivative algorithm to ensure that the PDI of the final product is stable at 1.2 - 1.5.

[0049] Step 5: The reaction effluent enters a vacuum distillation device to separate the ethyl acetate solvent. The recovered solvent is dried by molecular sieves and recycled. The distillation residue is cooled to room temperature, and analytical pure n-hexane is added for precipitation. The white flocculent polymer crude product is separated by a centrifuge.

[0050] Step 6: Dissolve the polymer crude product in HPLC-grade tetrahydrofuran, wash it successively with deionized water, and further purify the washed organic phase through a chromatography column filled with neutral alumina. The purified solution is evaporated to remove the solvent by a rotary evaporator to obtain a transparent polymer. The transparent polymer is placed in a vacuum drying oven for drying treatment to finally obtain a light yellow powdery viscosity reducer.

[0051] Step 7: Conduct multi-dimensional performance tests on the dried product, including measuring the molecular weight and distribution by gel permeation chromatography, measuring the oil solubility by the equilibrium solubility method, measuring the viscosity reduction performance by a rotary viscometer, and measuring the thermal stability by thermogravimetric analysis. After passing the tests, it is packaged and stored.

[0052] In one embodiment of the present invention: In step one, the purity of the selected methyl oleate monomer is ≥98%. The methyl oleate monomer and the analytical pure styrene monomer are put into a stainless-steel raw material tank according to a molar ratio of 3 - 3.5:1. Start stirring and stir at a speed of 200 rpm - 300 rpm. At the same time, heat up to 40°C - 45°C until a homogeneous mixture is formed. Weigh a visible light-responsive catalyst oxanthrene anthracene derivative accounting for 0.05% - 0.1% of the total monomer mass. It has a conjugated anthracene ring skeleton and symmetrically distributed alkyl substituents, and can improve the light absorption efficiency through intramolecular π-π conjugation effect. Through the regulation of intramolecular π-π conjugation effect and the steric hindrance of the alkyl chain, the molar extinction coefficient of the catalyst at 420 nm - 480 nm is ≥2.8×10 4 M -1 cm -1 , and dissolve the catalyst in anhydrous ethyl acetate with a water content of 0.05% - 0.1% to prepare a catalytic solution with a concentration of 0.5 mol / L - 0.7 mol / L.

[0053] In one embodiment of the present invention: In step two, pump the monomer mixture and the catalytic solution into a premixing tank with jacket temperature control according to a volume ratio of 13 - 15:1, and stir at a speed of 300 rpm - 500 rpm for 10 min - 20 min in an environment of 25°C - 35°C to ensure uniform dispersion of the catalyst. Subsequently, the material passes through a filter with an internal 0.1 μm - 0.2 μm ceramic membrane to remove impurity particles under a filtration pressure of 0.3 MPa - 0.5 MPa.

[0054] In one embodiment of the present invention: In step three, inject the reaction precursor solution into a quartz microchannel reactor with an inner diameter of 80 μm - 100 μm at a flow rate of 1.2 mL / min - 1.5 mL / min. The total length of the channel is 70 cm - 100 cm. An LED light source group with a wavelength of 385 nm - 450 nm is surrounded outside the reactor. Stabilize the light intensity at 15 mW / cm 2 -20 mW / cm 2 through a light intensity regulator. The catalyst absorbs photon energy to initiate the alternating copolymerization of the carbon-carbon double bonds of methyl oleate and styrene under a constant temperature condition of 25°C - 35°C. The specific reaction equation is as follows:

[0055] Catalyst excitation, after the catalyst (cat) absorbs a photon (hv), it transitions from the ground state to the excited state (cat * ):

[0056]

[0057] Free radical initiation, the excited state catalyst (cat *) Initiate the formation of free radical intermediates from methyl oleate (M1, CH3(CH2)7CH=CH(CH2)7COOCH3):

[0058]

[0059] Alternating chain growth: The free radical intermediate undergoes an addition reaction with styrene (M2, CH2=CHC6H5), and then continues to alternately add with methyl oleate to grow the polymer chain:

[0060]

[0061] Overall polymerization reaction formula: Generally speaking, n monomers of methyl oleate and n monomers of styrene undergo an alternating copolymerization reaction under the action of the excited state of the catalyst (cat * ) to produce an alternating copolymer:

[0062]

[0063] The residence time of the material in the microchannel is controlled within 2 min - 3 min. Through microscale efficient mass transfer and light intensity uniformity, the monomer conversion rate ≥ 98% is achieved, and the alternating connection rate of methyl oleate and styrene is ≥ 95% as detected by 1 1H-NMR.

[0064] In one embodiment of the present invention: In step four, when the detected value deviates from the target range (1.2 ≤ PDI ≤ 1.5), the control system automatically adjusts the reaction temperature and the material flow rate according to the following formula:

[0065]

[0066] where, ΔT is the temperature adjustment amount (°C), K pT is the proportional coefficient of temperature adjustment, and its value range is 0.5 - 1.2, K iT is the integral coefficient of temperature adjustment, and its value range is 0.1 - 0.3, K dT is the differential coefficient of temperature adjustment, and its value range is 0.05 - 0.2;

[0067] v new = v old · [1 + α · (PDI set - PDI real ) + β∫(PDI set - PDI real )dt]

[0068] where, v new is the corrected flow rate (mL / min), v oldis the current flow rate, the proportional correction factor α = 0.05 - 0.15, and the integral correction factor β = 0.01 - 0.05;

[0069] Through the above differential regulation strategy, ensure that the PDI of the final product is stable at 1.2 - 1.5, and the response time of the regulation system < 15 s.

[0070] In an embodiment of the present invention: In step five, the ethyl acetate solvent is separated by a vacuum distillation device under the conditions of a vacuum degree of 10 kPa - 20 kPa and a temperature of 40 - 50 °C, and 5 - 8 times the volume of analytical pure n - hexane is added for precipitation. The rotation speed of the centrifuge is 5000 rpm - 7000 rpm, and the time is 10 min - 20 min.

[0071] In an embodiment of the present invention: In step six, the dissolution concentration of the polymer crude product in tetrahydrofuran is 20 g / L - 30 g / L. It is washed 3 - 5 times with deionized water of equal volume in sequence, and the washing time for each time is 8 min - 12 min to remove the residual catalyst and monomer. The column diameter of the purification chromatography column is 1 cm - 3 cm, and the column height is 20 cm - 40 cm. Control the flow rate to be 0.5 mL / min - 1.5 mL / min. The purified solution is removed of the solvent by a rotary evaporator under the conditions of a temperature of 50 °C - 60 °C and a vacuum degree of 20 kPa - 30 kPa to obtain a transparent polymer. The polymer is placed in a vacuum drying oven and dried for 10 h - 12 h under the conditions of a temperature of 60 °C - 70 °C and a vacuum degree < 15 kPa.

[0072] In an embodiment of the present invention: In step seven, molecular weight and distribution: Measured by gel permeation chromatography, the mobile phase is tetrahydrofuran, the flow rate is 1.0 mL / min - 1.5 mL / min, and polystyrene is used as the standard sample. It is required that the number - average molecular weight M n = 15000 Da - 35000 Da, and the molecular weight distribution index PDI ≤ 1.5;

[0073] The oil solubility is determined by the equilibrium solubility method: Weigh 2.0 g - 2.2 g of the sample and add it to 20 mL - 23 mL of heavy oil at 50 °C - 52 °C. The viscosity of the heavy oil > 1000 mPa·s, and the asphaltene content is 15% - 20%. After stirring and dissolving, centrifuge, the centrifuge rotation speed is 3000 rpm - 3100 rpm, and centrifuge for 5 min - 7 min. Calculate the solubility ≥ 50 g / L;

[0074] The viscosity - reducing performance is measured by a rotary viscometer: Use a rotary viscometer to measure the viscosity of the heavy oil containing 2% viscosity - reducing agent under the conditions of a shear rate of 100 s -1 -110 s -1 and a temperature of 50 °C - 52 °C. It is required that the viscosity - reducing rate ≥ 80%;

[0075] Thermal stability determined by thermogravimetric analysis: Through thermogravimetric analysis, under nitrogen atmosphere and heating rate of 10℃ / min-12℃ / min, the initial decomposition temperature is >180℃;

[0076] The qualified products are packaged in aluminum foil bags by batches, attached with quality reports, and stored in an environment with a temperature of 20℃-30℃ and a humidity of less than 60%.

[0077] In one embodiment of the present invention, the visible light responsive catalyst selected is a xanthene anthracene derivative, the intramolecular conjugated anthracene ring skeleton of which can effectively expand the range of π electron delocalization, and the symmetrically distributed ethyl substituent (C2H5) can inhibit intermolecular aggregation through the steric hindrance effect, thereby improving the light absorption efficiency. The molar absorption coefficient of the catalyst in the wavelength range of 420-480nm is 3.0×10 4 M -1 cm -1 , which is consistent with the light absorption properties of efficient photocatalysts reported in the literature. In addition, through molecular dynamics simulation, its excited state lifetime is 5.2ns, indicating that it has the ability to stably initiate free radical polymerization.

[0078] In one embodiment of the present invention: the alternating copolymerization reaction is achieved through the selective interaction between the excited state of the catalyst and the monomer. Specifically, the carbon-carbon double bond of methyl oleate is more easily captured by cat to generate free radical intermediates due to the electron-withdrawing effect of the ester group, while the double bond of styrene is stabilized by the conjugation of the benzene ring and needs to be activated through an electron transfer mechanism. In order to further inhibit the self-polymerization of styrene, the present invention reduces the local concentration of M2 by adjusting the monomer feed ratio (methyl oleate: styrene = 3-3.5:1) and the short residence time (2-3min) of the microchannel reactor, thereby reducing homopolymerization by-products.

[0079] In one embodiment of the present invention: the PID control algorithm accurately controls the chain growth and termination rates by dynamically compensating for the reaction temperature and material flow rate;

[0080] Example 1, please refer to the attached Figure 1 , Rapid synthesis of oil-soluble heavy oil viscosity reducer

[0081] 1. Raw material preparation and pretreatment

[0082] Monomer mixing:

[0083] Methyl oleate: weigh 102.15 g (0.3 mol) of methyl oleate with a purity of 98.5%;

[0084] Styrene: analytically pure styrene 10.415 g (0.1 mol);

[0085] Molar ratio of substances: methyl oleate: styrene = 3:1;

[0086] Charge into a 500 mL stainless steel raw material tank, start stirring at a speed of 250 rpm, heat up to 42 °C, and continuously stir for 30 minutes until a clear homogeneous mixture is formed;

[0087] Catalyst preparation:

[0088] Weigh a visible light-responsive catalyst, xanthenoanthracene derivative, which accounts for 0.07% of the total monomer mass. It contains a conjugated anthracene ring skeleton and symmetric C2H5 substituents. The total monomer mass = 102.15 g + 10.415 g = 112.565 g, and the catalyst dosage = 112.565 g × 0.07% = 0.0788 g;

[0089] Dissolve it in 100 mL of anhydrous ethyl acetate with a water content of 0.08% to prepare a 0.6 mol / L catalytic solution (the molar extinction coefficient at 420 nm is measured to be 3.0×10 4 M -1 cm -1 );

[0090] II. Premixing and impurity filtration

[0091] Pump the monomer mixture and the catalytic solution into a 250 mL jacketed premixing tank and stir at 400 rpm for 15 min at 30 °C;

[0092] The material passes through a filter with a built-in 0.15 μm ceramic membrane (filtration pressure 0.4 MPa) to remove particles with a particle size > 50 nm, and 125 mL of clear precursor solution is obtained.

[0093] III. Microfluidic photocatalytic polymerization

[0094] Reactor parameters: Quartz microchannel reactor (inner diameter 80 μm, total length of spiral channel 80 cm, effective volume 1.2 mL), peripheral LED light source group (wavelength 405 nm, light intensity 18 mW / cm 2 );

[0095] Polymerization reaction: The precursor solution is injected into the reactor at a flow rate of 1.3 mL / min and reacts at a constant temperature of 30 °C;

[0096] Reaction monitoring: Monitor the monomer conversion rate up to 98.5% through an online ultraviolet spectrometer, 1 The alternating connection rate of methyl oleate and styrene is detected by 1H-NMR to be 96%;

[0097] IV. Molecular weight distribution regulation

[0098] A laser particle size analyzer and a multi-angle light scattering analyzer are connected in series at the outlet end to continuously monitor M n = 20,000 Da, M w= 25,000 Da, the calculated PDI = 1.25 (within the target range of 1.2 - 1.5, no adjustment required).

[0099] V. Solvent Recovery and Crude Product Separation

[0100] The reaction effluent enters a vacuum distillation column (vacuum degree 15 kPa, temperature 45 °C) to recover 96% ethyl acetate solvent;

[0101] The distillation residue is cooled to 25 °C, 5 times the volume (625 mL) of analytical pure n - hexane is added, and it is centrifuged at 6000 rpm for 15 minutes to collect the white flocculent crude product (wet weight 48.2 g);

[0102] VI. Refining and Drying

[0103] It is dissolved in 200 mL of THF (concentration 24 g / L), washed 4 times (10 minutes each time), and purified by a chromatography column (column diameter 2 cm, column height 30 cm, flow rate 1.0 mL / min).

[0104] After rotary evaporation (55 °C, 25 kPa), it is vacuum - dried (65 °C, 10 kPa) for 10 hours to obtain 42.1 g of powder (purity 99.6%)

[0105] VII. Performance Testing

[0106] Molecular weight and distribution: GPC test (mobile phase THF, flow rate 1.0 mL / min) shows M n = 21,000 Da, M w = 26,000 Da, PDI = 1.24;

[0107] Oil solubility: 2.0 g of the sample is dissolved in 20 mL of heavy oil at 50 °C (viscosity 1200 mPa·s, asphaltene content 18%), and the solubility after centrifugation is 58 g / L;

[0108] Viscosity reduction rate: Measured by a Brookfield DV - III viscometer (100 s - 1, 50 °C), the viscosity reduction rate is 81.7%.

[0109] Thermal stability: TGA shows an initial decomposition temperature of 210 °C (nitrogen, 10 °C / min).

[0110] Example 2. Please refer to the appendix Figure 1 , Rapid Synthesis of Oil - Soluble Heavy Oil Viscosity Reducer

[0111] I. Raw Material Preparation and Pretreatment

[0112] Monomer Mixing:

[0113] Weigh 119.175 g (0.35 mol) of methyl oleate with a purity of 99% (molar mass 340.5 g / mol) and 10.415 g (0.1 mol) of styrene of analytical grade (molar mass 104.15 g / mol), with a molar ratio of 3.5:1;

[0114] Put them into a 1 L stainless steel raw material tank, with a stirring rate of 300 rpm, heat up to 45 °C, and stir for 25 minutes until homogeneous;

[0115] Catalyst preparation:

[0116] Weigh a catalyst accounting for 0.1% of the total monomer mass (total monomer mass = 119.175 g + 10.415 g = 129.59 g, catalyst dosage = 0.1296 g), dissolve it in 200 mL of anhydrous ethyl acetate with a water content of 0.06% to prepare a 0.55 mol / L catalytic solution (absorption coefficient at 420 nm is 2.9×10 4 M -1 cm -1 );

[0117] II. Premixing and impurity filtration

[0118] Pump the monomer mixture (150 mL) and the catalytic solution (11.5 mL, volume ratio 13:1) into a 500 mL jacketed premixing tank, stir at 35 °C and 500 rpm for 10 minutes;

[0119] Filter through a 0.2 μm ceramic membrane (pressure 0.5 MPa) to obtain 160 mL of precursor solution;

[0120] III. Microfluidic photocatalytic polymerization

[0121] Reactor parameters: inner diameter 100 μm, total channel length 100 cm, effective volume 3.14 mL, LED light source (385 nm, light intensity 20 mW / cm 2 );

[0122] The flow rate of the precursor solution is 1.5 mL / min (residence time = 3.14 mL ÷ 1.5 mL / min ≈ 2.09 minutes), react at 35 °C, monomer conversion rate is 98.8%, and alternating linkage rate is 95.5% ( 1 H-NMR);

[0123] IV. Molecular weight distribution regulation

[0124] Monitor M n = 28,000 Da, M w = 34,000 Da, PDI = 1.21;

[0125] V. Solvent recovery and crude product separation

[0126] Vacuum distillation (10 kPa, 50 °C) was used to recover 97% of the solvent. 8 times the volume (1280 mL) of n-hexane was added to the residual liquid, and it was centrifuged at 7000 rpm for 10 minutes to obtain 76.5 g of the crude product.

[0127] VI. Refinement and Drying

[0128] The crude product was dissolved in 300 mL of THF (concentration 25.5 g / L), washed 5 times (12 minutes each time), and purified by passing through a neutral alumina chromatography column (column diameter 3 cm, column height 40 cm, flow rate 1.5 mL / min).

[0129] After rotary evaporation (60 °C, 20 kPa), it was vacuum dried (70 °C, 8 kPa) for 12 hours to obtain 68.3 g of powder (purity 99.7%).

[0130] VII. Performance Testing

[0131] Molecular weight and distribution: M m = 27,500 Da, M w = 33,000 Da, PDI = 1.20.

[0132] Oil solubility: 2.2 g of the sample was dissolved in 23 mL of heavy oil at 52 °C (viscosity 1500 mPa·s, asphaltene content 20%), and the solubility was 55 g / L.

[0133] Viscosity reduction rate: At a shear rate of 110 s-1, the viscosity at 52 °C was 250 mPa·s, and the viscosity reduction rate was 83.3%.

[0134] Thermal stability: The initial decomposition temperature of TGA was 205 °C (nitrogen, 12 °C / min)

[0135] According to the content of the above examples, it can be concluded that by connecting a laser particle size analyzer and a multi-angle light scattering analyzer in series at the reactor outlet to monitor the molecular weight in real time, combining the proportional-integral-derivative algorithm to dynamically control the reaction temperature and the material flow rate, and performing multiple-step refinement treatments such as dissolving the polymer crude product in HPLC-grade tetrahydrofuran, washing with deionized water, purifying through a neutral alumina chromatography column, and vacuum drying, and at the same time using multi-dimensional detection methods such as gel permeation chromatography and equilibrium solubility method, the problems of uncontrollable molecular weight distribution and high impurity residue rate in the prior art are effectively solved. Through the synergistic effect of microfluidic photocatalytic polymerization and precise control technology, the molecular structure of the viscosity reducer is regularized and impurities are deeply removed. The prepared viscosity reducer has good dispersibility and high solubility in heavy oil, can efficiently destroy the gum-asphaltene network, and has stable long-term storage performance. The process parameters of the present invention have strong controllability and excellent product performance, providing an efficient and reliable technical solution for heavy oil exploitation, and having significant innovation and industrial application value.

[0136] Although the present invention is disclosed above in a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A rapid synthesis method of an oil-soluble viscous crude oil viscosity reducer, characterized in that, The synthesis method includes the following specific steps: Step 1: Mix methyl oleate monomer with analytical pure styrene monomer to prepare a homogeneous mixture. Weigh a visible light-responsive catalyst, xanthenoanthracene derivative, and dissolve the catalyst in anhydrous ethyl acetate to prepare a catalytic solution. Step 2: Pump the mixture and the catalytic solution into a premixing tank. After stirring, filter out impurities through an in-built filter to obtain a clear and transparent reaction precursor solution. Step 3: Inject the reaction precursor solution into a quartz microchannel reactor. An LED light source group surrounds the reactor. The catalyst absorbs photon energy to initiate the alternating copolymerization of the carbon-carbon double bonds of methyl oleate and styrene, forming a pre-polymer of an oil-soluble viscosity reducer. Step 4: Connect a laser particle size analyzer and a multi-angle light scattering analyzer in series at the reactor outlet to monitor in real time the number average molecular weight (M n ) and the weight average molecular weight (M w ) of the polymer, calculate the molecular weight distribution index PDI = M n / M w , and dynamically adjust the reaction temperature and the material flow rate based on the proportional-integral-derivative algorithm to ensure that the PDI of the final product is stable within a preset range; Step 5: The reaction effluent enters a vacuum distillation device to separate the ethyl acetate solvent. The recovered solvent is dried by molecular sieve and recycled. The distillation residue is cooled to room temperature, and analytical pure n-hexane is added for precipitation. The white flocculent polymer crude product is separated by a centrifuge. Step 6: Dissolve the polymer crude product in HPLC-grade tetrahydrofuran and wash it with deionized water. The washed organic phase is further purified through a chromatography column filled with neutral alumina. The solvent in the purified solution is removed by a rotary evaporator to obtain a transparent polymer. The transparent polymer is placed in a vacuum drying oven for drying treatment to obtain a light yellow powdery viscosity reducer. Step 7: Conduct multi-dimensional performance testing on the dried product, including measuring the molecular weight and distribution by gel permeation chromatography, measuring the oil solubility by the equilibrium solubility method, measuring the viscosity reduction performance by a rotary viscometer, and measuring the thermal stability by thermogravimetric analysis. After passing the tests, it is packaged and stored.

2. A rapid synthesis method of an oil-soluble heavy oil viscosity reducer according to claim 1, characterized in that: In the first step, the purity of the selected methyl oleate monomer is ≥98%. The methyl oleate monomer and the analytical pure styrene monomer are put into a stainless-steel raw material tank according to the molar ratio of 3 - 3.5:

1. Stirring is started and the mixture is stirred at a speed of 200 rpm - 300 rpm. At the same time, the temperature is raised to 40°C - 45°C until a homogeneous mixture is formed. Weigh a visible light-responsive catalyst, xanthenoanthracene derivative, which accounts for 0.05% - 0.1% of the total mass of the monomers, and the molar extinction coefficient of the catalyst at 420 nm - 480 nm is ≥2.8×10 4 M -1 cm -1 . The catalyst is dissolved in anhydrous ethyl acetate with a water content of 0.05% - 0.1% to prepare a catalytic solution with a concentration of 0.5 mol / L - 0.7 mol / L.

3. A rapid synthesis method of an oil-soluble viscous crude oil viscosity reducer according to claim 1, characterized in that: In Step 2, the monomer mixture and the catalytic solution are pumped into a jacketed temperature-controlled premixing tank at a volume ratio of 13 - 15:1, stirred at a speed of 300 rpm - 500 rpm for 10 min - 20 min in an environment of 25°C - 35°C, and then the material passes through a filter with an in-built 0.1μm - 0.2μm ceramic membrane to remove impurity particles under a filtration pressure of 0.3 MPa - 0.5 MPa.

4. A rapid synthesis method of an oil-soluble viscous crude oil viscosity reducer according to claim 1, characterized in that: In the third step, the reaction precursor solution is injected into a quartz microchannel reactor with an inner diameter of 80 μm - 100 μm at a flow rate of 1.2 mL / min - 1.5 mL / min. The total length of the channel is 70 cm - 100 cm. An LED light source group with a wavelength of 385 nm - 450 nm is surrounded around the reactor. The light intensity is stabilized at 15 mW / cm 2 - 20 mW / cm 2 . The catalyst absorbs the photon energy to initiate the alternating copolymerization of the carbon-carbon double bonds of methyl oleate and styrene under the constant temperature condition of 25°C - 35°C. The specific reaction equation is as follows: Catalyst excitation. After the catalyst (cat) absorbs a photon (hv), it transitions from the ground state to the excited state (cat * ): Free radical initiation, the excited state catalyst (cat * ) initiates the formation of free radical intermediates from methyl oleate (M1, CH3(CH2)7CH=CH(CH2)7COOCH3): Alternating chain growth occurs. The radical intermediate undergoes an addition reaction with styrene (M2, CH2=CHC6H5), and then continues to alternately add with methyl oleate to grow the polymer chain: Overall polymerization reaction equation: generally speaking, n methyl oleate monomers and n styrene monomers undergo an alternating copolymerization reaction under the action of the excited state of the catalyst (cat * ), generating an alternating copolymer: The residence time of the material in the microchannel is controlled within 2 min - 3 min.

5. A rapid synthesis method of an oil-soluble heavy oil viscosity reducer according to claim 1, characterized in that: In Step 4, when the detected value deviates from the target range (1.2 ≤ PDI ≤ 1.5), the control system automatically adjusts the reaction temperature and the material flow rate according to the following formula: where, ΔT is the temperature adjustment amount (°C), K pT is the proportionality coefficient of temperature adjustment, and its value range is 0.5 - 1.2, K iT is the integral coefficient of temperature adjustment, and its value range is 0.1 - 0.3, K dT is the differential coefficient of temperature adjustment, and its value range is 0.05 - 0.2; v new = v old · [1 + α·(PDI set - PDI real ) + β∫(PDI set - PDI real )dt] Among them, v new is the corrected flow rate (mL / min), v old is the current flow rate, the proportional correction factor α = 0.05 - 0.15, and the integral correction factor β = 0.01 - 0.05; Through the above differential regulation strategy, ensure that the PDI of the final product is stably within the preset range of 1.2 - 1.5, and the response time of the regulation system < 15 seconds.

6. A rapid synthesis method of an oil-soluble heavy oil viscosity reducer according to claim 1, characterized in that: In Step 5, the vacuum distillation device separates the ethyl acetate solvent under a vacuum of 10 kPa - 20 kPa and a temperature of 40 - 50°C, adds 5 - 8 times the volume of analytical pure n-hexane for precipitation, and the centrifuge speed is 5000 rpm - 7000 rpm for 10 min - 20 min.

7. A rapid synthesis method of an oil-soluble heavy oil viscosity reducer according to claim 1, characterized in that: In the sixth step, the dissolution concentration of the crude polymer in tetrahydrofuran is 20 g / L - 30 g / L. It is washed 3 - 5 times with equal - volume deionized water in sequence, and the washing time for each time is 8 min - 12 min. The purified chromatography column has a column diameter of 1 cm - 3 cm and a column height of 20 cm - 40 cm. The flow rate is controlled at 0.5 mL / min - 1.5 mL / min. The purified solution is de - solventized by a rotary evaporator at a temperature of 50 °C - 60 °C and a vacuum degree of 20 kPa - 30 kPa to obtain a transparent polymer. The polymer is placed in a vacuum drying oven and dried for 10 h - 12 h at a temperature of 60 °C - 70 °C and a vacuum degree < 15 kPa.

8. A rapid synthesis method of an oil-soluble heavy oil viscosity reducer according to claim 1, characterized in that: In step 7, molecular weight and distribution: determined by gel permeation chromatography, with tetrahydrofuran as the mobile phase, flow rate 1.0 mL / min - 1.5 mL / min, using polystyrene as the standard sample, and the number average molecular weight M n = 15000 Da - 35000 Da, and the molecular weight distribution index PDI ≤ 1.5; The oil - solubility is determined by the equilibrium solubility method: Weigh 2.0 g - 2.2 g of the sample and add it to 20 mL - 23 mL of heavy oil at 50 °C - 52 °C. The viscosity of the heavy oil > 1000 mPa·s and the asphaltene content is 15% - 20%. After stirring and dissolving, centrifuge it at a centrifuge speed of 3000 rpm - 3100 rpm for 5 min - 7 min, and calculate the solubility ≥ 50 g / L. Measuring the viscosity reduction performance with a rotational viscometer: Use a rotational viscometer to measure the viscosity of heavy oil containing 2% viscosity reducer under the conditions of shear rate 100 s -1 -110 s -1 and temperature 50°C - 52°C, and the viscosity reduction rate is required to be ≥80%; The thermal stability is determined by thermogravimetric analysis: Through thermogravimetric analysis, under the conditions of a nitrogen atmosphere and a heating rate of 10 °C / min - 12 °C / min, the initial decomposition temperature > 180 °C. The qualified products are packaged in aluminum foil bags by batch, accompanied by a quality report, and stored in an environment with a temperature of 20 °C - 30 °C and a humidity < 60%.

Images